When such conventional vacuum toilets are operated, the flushing is started by operating the trigger mechanism. As a result, flushing liquid, such as water is supplied, and thereafter the suction valve is opened for flushing the waste out of the toilet bowl and into the collection container. The transport of the waste is accomplished by a pressure difference between the collecting container and the toilet bowl. As a result, a rush of air is generated which in turn produces substantial noise and such noise is even amplified by the funnel effect of the toilet bowl. It is desirable to avoid or at least diminish such noise generation or to damp its effect.